The proposed project will study the relationships between protein deficiency and reproduction. The effect of a low protein diet (LPD), consisting of 8% protein, will be examined in male Sprague-Dawley rats from 20 days of age through day 80. Hypothalamic luteinizing hormone-releasing hormone, serum and pituitary concentrations of luteinizing hormone, follicle stimulating hormone and prolactin, and serum testosterone will be quantitated by radioimmunoassay. These hormones will be measured at selected time intervals within the 60 day experimental period. Light and electron microscopic analyses of the anterior pituitary gland, sex accessory organs and gonads will also be conducted. An assessment of the LPD on fertility will be made once the animals have reached 50 days of age. Experimental observations made from these studies will be compared to data gathered from age-matched control rats fed a 27% protein diet.